const fp = require('lodash/fp')
// 数据
// horsepower 马力, dollar_value 价格, in_stock 库存
const cars = [
    { name: 'Ferrari FF', horsepower: 660, dollar_value: 700000, in_stock: true },
    { name: 'Spyker C12 Zagato', horsepower: 650, dollar_value: 648000, in_stock: false },
    { name: 'Jaguar XKR-S', horsepower: 550, dollar_value: 132000, in_stock: false },
    { name: 'Audi R8', horsepower: 525, dollar_value: 114200, in_stock: false },
    { name: 'Aston Martin One-77', horsepower: 750, dollar_value: 1850000, in_stock: true },
    { name: 'Pagani Huayra', horsepower: 700, dollar_value: 1300000, in_stock: false },
]

// 练习1 使用函数组合fp.flowRight()重新实现下面这个函数
let isLastInStock = function(cars) {
    // 获取最后一条数据
    let last_car = fp.last(cars)
    // 获取最后一条数据的in_stock属性值
    return fp.prop('in_stock', last_car)
}
// 练习1答案
let isLastInStockCompose = fp.flowRight(fp.prop('in_stock'), fp.last)
console.log('练习1答案调用结果', isLastInStockCompose(cars))

// 练习2 使用fp.flowRight(),fp.prop()和fp.first()获取第一个car的name
// 练习2答案
let getFirstName = fp.flowRight(fp.prop('name'), fp.first)
console.log('练习2答案调用结果', getFirstName(cars))

// 练习3: 使用帮助函数_average重构averageDollarValue，使用函数组合的方式实现
let _average = function(xs) {
    return  fp.reduce(fp.add, 0, xs) / xs.length
}
let averageDollarValue = function(cars) {
    let dollar_values = fp.map(function(car) {
        return car.dollar_value
    }, cars)
    return _average(dollar_values)
}
console.log(averageDollarValue(cars))
// 练习3答案
let averageDollarValueCompose = fp.flowRight(_average, fp.map(car => car.dollar_value))
console.log('练习3答案调用结果', averageDollarValueCompose(cars))

// 练习4: 实现sanitizeNames()函数
let _underscore = fp.replace(/\W+/g, '_')
let sanitizeNames = fp.map(fp.flowRight(_underscore, fp.toLower))
console.log('练习4答案调用结果', sanitizeNames(['Hello World']))